Republic Book 1 and its relation to the rest of the Republic

A.
Book 1 reads in many respects as an earlier work of Plato which has
been re-used to serve as an introduction to the main body of the Republic.

1.
It has the form of a Socratic dialogue typical of Plato’s earlier
works, but from which he has moved away by the time of the main body
of the Republic
(a) It contains genuine dialogue, with people other than Socrates
expressing their own ideas and quite fully developed as characters.
Except for the presentation by Glaucon and Adeimantus at the beginning
of Book 2, the rest reads as an interrupted monologue by Socrates,
with the rest having no ideas or distinctive character of their own

(b) It shows up a so-called expert as no knowing what he thought
he did, and it ends inconclusively with Socrates admitting that he
still does not know the answer to the main question (354b). By contrast,
Socrates is set up near the beginning of Book 2 (258a and 368a-d)
as the expert who can answer the questions, though he is initially
reluctant to admit it, and he proceeds to expound his ideas for the
rest of the work.

(c) The subject matter is the definition of a virtue. The rest of
the Republic, apart from giving the definition (which never happens
in the early works), extends into provisions for the ideally just
state, a theory of knowledge and being, a theory of the soul, a classification
of political constitutions etc)

2.
The rest of the Republic is presented as Socrates’ response
to the challenge raised by Glaucon and Adeimantus in Book 2, and therefore,
strictly speaking, Book 1 is irrelevant to the argument. The attempt
to make Book 2 follow naturally from Book 1 seems artificial: Socrates
is presented as having refuted Thrasymachus’ argument in Book
1 while still not knowing at the end what justice is. Glaucon makes
it clear (357b) that he is not convinced by Socrates’ arguments
against Thrasymachus. (Is Plato perhaps signaling that he is no longer
satisfied with the arguments of Book 1 himself?) Both Glaucon (358b-c)
and Adeimantus (367a) are made to present their case as an extension
of Thrasymachus’ arguments, yet while their general standpoint
is very similar to his, they use arguments that are very different.
Glaucon, for instance, presents justice as a particular kind of good,
whereas Thrasymachus did not regard it as good at all. They also present
their respective cases at great length as though the issues had not
been thoroughly aired before.

B.
Book 1 may well have started out independently, but it does in fact
introduce some of the issues of Books 2 – 10, possibly even
adapted by Plato for the purpose.
1.
It has been suggested that Plato was sensitive about his refusal to
follow a political career in Athens. Instead he constructs an ideal
political world, but is at pains to present it as the answer to the
shortcomings of the world he actually lives in. So he has thought
through and rejected the conventional ideas of Cephalus and Polemarchus,
and the radical sophistic ideas of Thrasymachus and those who have
influenced Glaucon and Adeimantus, as well as the Athenian political
systems too (Book 8).

2.
Cephalus is someone for whom the amassing of wealth has taken precedence
over thinking about moral issues or active citizenship. Thrasymachus
poses as an expert on moral and political philosophy, and charges
a heavy fee for his supposed expertise. As the Republic develops we
find that the people who are to be involved in political life are
the true experts in moral and political philosophy, and they are neither
engaged in any wealth creating activity nor even allowed to own private
property.

3.
Cephalus also raises the question of old age. Now that he is old –
too old for sexual passion – he claims he feels disposed to
take part in philosophical discussion. He makes a quick exit though
when the discussion gets difficult. Plato also reserves philosophy
until the end of a very long education, and his philosopher rulers
are older people; however, they are limited to those who are by nature
always able to restrain their appetites.

4.
Cephalus regards justice as relatively unimportant – one can
wait till old age before thinking much about it. Polemarchus sees
it as a skill aiming at a trivial end. Already in Book 1 (335c) Plato
describes justice as the human excellence, and this view is developed
in the account of the individual justice in Book 4. A shortcoming
of Polemarchus’ view is that justice could be a skill for doing
harm – i.e. goodness is not essential to his concept of justice.
Thrasymachus does not regard justice as good at all. Plato’s
undertaking as the main item on the Republic’s agenda is to
show that justice is good both in itself and in its consequence. Of
course Glaucon also questions the goodness of justice in Book 2; perhaps
Plato wants to use Book 1 to emphasise that people in general only
pay lip service to justice as an important human virtue, and so the
argument of the Republic is very necessary.

5.
While both Glaucon and Thrasymachus admire the tyrant as the supremely
happy man, it is Thrasymachus who has more to say about him specifically
as a ruler. In some respects he gives us a distorted anticipation
of Plato’s own later theory. The ruler alone is in a position
to define the nature of justice by making it up to suit himself. He
is like a shepherd who is concerned about his flock – to fatten
them up for his own peofit. In Socrates’ reply to this (347)
Plato anticipates his later demand that the guardians will have to
sacrifice their own preferences and be compelled to rule. In 342 d-e
Plato introduces his favourite analogies for the role of ruler, namely
those of the doctor and the ship’s capatain.

6.
A fundamental feature of Thrasymachus’ position is his assumption
that society is a battleground of conflicting individual interests.
Plato is constantly at pains to emphasise the importance of unity
in the ideal state, so it has to be a fundamental feature of his theory
that there is no conflict between people’s real interests at
all.